In the aforementioned copending patent application, owned by the assignee of the present invention, there is described a method and apparatus for passive coupling to individual signal lines on a computer data channel, and for monitoring the data passed thereover. The described apparatus is a channel analyzer system having logic circuits which have a preselectable capability for recognizing transmitted data of interest for further analysis. The channel analyzer system further includes a large storage area for retaining preselected amounts of data, and circuits for examining blocks of data so collected. The channel analyzer also includes circuits and software for labeling data samples with an identifier, displaying selected portions of the samples, including representative values signifying the data content and the content of data identified with preselected signal lines. The channel analyzer is capable of identifying preselected signal line changes, and monitoring the data channel activity prior to and subsequent to the occurrence of a preselected signal line event of interest.
The aforementioned channel analyzer system is capable of monitoring the considerable number of signal lines associated with a particular computer input/output channel. In a sense these channels accommodate information transfer in parallel flow arrangement, the total number of signal lines which may be simultaneously monitored is variable, depending upon the parallel data transfer capability, or word size, of a particular data processing system. It is not unusual for data processing systems to utilize channels having 35 or more parallel transmission paths. In the preferred embodiment of the channel analyzer described above the capability of connecting to and simultaneously monitoring 35 parallel lines is described.
A particular computer processing system may have a plurality of input and output channels, each channel having a predetermined number of parallel transmission paths, and it is desirable to provide the capability for the aforementioned channel analyzer to monitor more than a single channel. Multiple channel monitoring need not necessarily be simultaneously accomplished, but should be capable of accomplishment within a relatively short time frame. It is generally unsatisfactory to require all of the channel analyzer input conductors to be manually disconnected from a first computer channel and then manually reconnected to a second computer channel; this would require disconnecting more than 70 conductors from a first computer channel and then reconnecting the more than 70 input conductors to a second computer channel. It is preferable that all of the channel conductors to be monitored be initially connected during the time the channel analyzer is set up, when the monitored computer system or systems is shut down, and the conductors are left in place while the computer system or systems are operational. Manually disconnecting and reconnecting a large number of conductors is wasteful of computer time, and is usually not tolerable in an operational computer center environment.
There is therefore a need for a device which permits an initial hookup of all possible channel conductors for which monitoring is desired, and which may remain connected during operation of the computer system, without interference with any of the normal computer operational sequences.
In a typical computer center environment there may be a number of data processing systems operating simultaneously and independently of one another. Such systems are typically operated continuously, except for periodic set schedules for routine maintenance. Whenever a circuit failure occurs in any of these systems it is extremely important that the failure be isolated as soon as possible, so that repairs can be made with a minimum of lost time, to permit the system to resume operations as soon as possible. The channel analyzer described above is a valuable tool for assisting in the location and isolation of defective circuits, and it is therefore desirable to connect the channel analyzer to the input/output channels of a computer system which is experiencing circuit problems in order for the problem to be corrected. There is therefore a need for a connection device which will permit a rapid and efficient connection of the channel analyzer to the computer input/output channels, without disturbing the operation of other computer systems which may be operational at the same time. It is preferable to have the computer input/output channel connections made ahead of time, so that upon occurrence of a fault condition the channel analyzer can be immediately switched into a monitoring operation with respect to the various computer processor input/output channels, thereby minimizing maintenance delays.